“GDR" – stands for "General Redistribution Release", implies that this is a complete new release, based on a new architecture. Architectural changes from the Rosario project (Visual Studio Team System 2010) have been taken and rolled forward in time to provide new features and extensibility points as well as to align the release with Visual Studio Team System 2010 release.

MSDN Download: http://www.microsoft.com/downloads/details.aspx?FamilyID=bb3ad767-5f69-4db9-b1c9-8f55759846ed&displaylang=en

For more info about this release, please visit http://blogs.msdn.com/gertd/archive/2008/11/25/visual-studio-team-system-2008-database-edition-gdr-rtm.aspx